Prestolite w/ Mopar issues

Discussion in 'Injection Tech' started by Meat Man, Oct 7, 2019.


  1. Meat Man

    Meat Man Farmall Cub

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    Bill, I have a bunch of pictures and would like to add to your writeup. It has been several years since I have added pictures, I will figure out how to do it .

    In the mean time, anyone give any help with troubleshooting? This is with vac advance for a carb.
    [​IMG]
    Pickup coil ohms at 250 ohms when not spinning (0.25 on 20K scale). It does change resistance when I spin the shaft.
    When I put the meter in continuity test, I can make the buzzer beep when I spin it.

    I am using BWD module # CB4P.
    According to this website, it checks out OK on ohms and voltage.
    http://gpzweb.s3-website-us-east-1.amazonaws.com/Ignition/HeiModules/HeiModules.html

    I have it test wired on my bench and it will not fire a coil/sparkplug.
    Using the wiring diagram in the other thread
    G = Pickup black
    W= Pickup yellow ( I even tried to reverse)
    B = 12 V and Coil +
    C = Coil -


    Bench testing seems fine.
    I got it to fire the motor one time and it sounded a little weak. Seemed like it needed more advance. I jumped a tooth both ways and now it won't fire in any position.

    One thing I noticed was that the module does not fire the coil consistently. (tested by going Battery + to Coil - with a light).
    Sometimes it is a long solid fire, other times it is just not steady. The motor will sputter while I crank, but it will not catch. Module has steady 12V in start and run.

    The wiring is still temporary, could it just be induced voltage from plug wires?
     
  2. Bill USN-1

    Bill USN-1 Moderator Staff Member Moderator

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    When you reply, just click the "upload a file" button in the lower right.
    Then you can add as many as you want.
    If they are bigger than 800x600 then only show as thumbnails not full size.
    I would like to see pics of your setup including the module.

    As for your testing, you never measure resistance when voltage is applied.
    When you spin the shaft you are creating an AC voltage.
    If the resistance is good and it creates an AC voltage that increases as the rpm increases, then the pick up is good.
    Air gap should be about .008 to ensure low speed (cranking) operation.

    If you don't have a proper alum heat sink with thermal paste and your not properly grounding the heat sink, then the module will burn up within about 30sec.
    You can take it back and some parts stores can test it.
    This is an 800x600 pic
    DSC05562 (800x600).jpg
     
    Last edited: Oct 7, 2019
  3. Meat Man

    Meat Man Farmall Cub

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    Thanks!

    Yes, I have good heat sink. I polished the spot for a good ground. The only thing I did not test successfully was the AC voltage output. I was just spinning it by hand and my cheap meter wasn't registering it.

    I'll have to measure the air gap. It is set at "business card" thickness.

    Pics to follow. They are on my home PC.
     
  4. Meat Man

    Meat Man Farmall Cub

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    Aligned the pickup in the same location as stock (in-line with the pivot pin and the vacuum advance attachment. Required welding an extension onto the baseplate, modification of the pickup mounting. Tried to show it with the green line in the photo, but image is skewed.

    I think I need to align the timing mark on the motor. I know I am not 180* off, but I am off at least one tooth.
    Then I will drill a new hole in my old cap and double check phasing at #8 plug.

    After that, I guess I will try a new module. Pretty sure I am getting consistent trigger on the pickup.

    20190827_193750.jpg Completed.jpg
     
  5. Meat Man

    Meat Man Farmall Cub

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    It Verks!

    I was 2 teeth off. Phasing was spot on.

    Made the wiring more permanent, and it appears good to go. Still has to crank a couple of times before it will fire the coil. For now, I will assume that is normal.

    Thanks Bill!
     

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